| The GONG (Global Oscillation Network Group) network consists of 6 automated observing stations around the world. The original 256x256 pixel instruments observed from 1995 to 2001, providing quasi-continuous, medium-degree helioseismic data with a duty cycle around 85%. The network was then upgraded to the 'GONG+' 1024x1024 pixel cameras, which allow us to detect modes up to around l=1000. The upgrade means that we can now apply the techniques of local helioseismology to monitor flows close to the surface, as well as continuing global helioseismology with the medium-l p modes that probe rotation and structure well into the solar interior. |
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